Refrigeration power plant

ABSTRACT

The invention relates to a power station comprising at least one steam turbine and/or gas turbine which is connected to at least one absorption type refrigeration machine in order to produce refrigeration, whereby the absorption type refrigeration machine is operated by means of steam which is taken from the steam turbine, or by means of waste heat produced by the gas turbine.

CROSS REFERENCE TO RELATED APPLICATION

This application is the US National Stage of International ApplicationNo. PCT/DE03/00857, filed Mar. 17, 2003 and claims the benefit thereof.The International Application claims the benefits of German Patentapplication No. 10214183.5 DE filed Mar. 28, 2002, both of theapplications are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The invention relates to a power station having at least one steamturbine and/or at least one gas turbine.

BACKGROUND OF THE INVENTION

One of today's major objectives to be met by technological means is toensure the economical handling of available energy resources ingenerating and consuming power.

Power plants which are sizeable in terms of their installed generatingcapacity and which supply a large number of consumers and extensivegeographical areas with electrical energy and district heat on acentralized basis are frequently employed to generate electrical energyand also to decouple district heat.

The centralized provisioning in this manner of electrical and thermalenergy is cost-effective compared to decentralized provisioningemploying a large number of smaller isolated plants and is particularlyeconomical in operation.

Said known, what is termed combined heat and power generation ispractically independent of the type of power station employed, the sizeof the power station, and the fuel used. The only crucial factor is fora heat source having a suitable primary-side temperature to be availablefor heating a heating medium. Hot water is today used almost exclusivelyas the heating medium.

To implement combined heat and power generation of the known type, heatthat would otherwise have to be entirely or at least substantiallydispersed unused into the surrounding area is usually decoupled from thepower-plant process.

The heat source used for combined heat and power generation of this typecan be, for example, steam from a steam turbine, which steam is taken,for instance, from a low-pressure section of the steam turbine. Theheating medium can then be heated by the extracted steam through thelatter's passing the condensation heat it contains to the heating mediumby means of heat exchange.

This type of heat provisioning by means of combined heat and powergeneration of the kind described is especially economical becauseotherwise unused process heat is rendered usable, for example forheating buildings.

Contrary to the cited central provisioning with electrical and thermalenergy, to generate refrigeration it is today known how to generate saidrefrigeration almost exclusively on a decentralized basis, mostly inblock-type thermal power stations, or directly on site, mostly on thedomestic premises themselves.

Said type of decentralized provisioning with refrigeration is verydemanding in terms of cost and energy because either block-type thermalpower stations have to be specially set up for the purpose of supplyingconsumers who have substantial refrigeration requirements or, in thecase of refrigeration provisioning carried out directly on domesticpremises, a large amount of electrical energy has to be expended inorder to generate the required amount of refrigeration.

SUMMARY OF THE INVENTION

The object of the invention is therefore to specify an economical meansof generating refrigeration.

Said object is achieved by providing a power station which is ableeconomically to meet a substantial need for refrigeration alongside aneed for mechanical (generally: electrical) energy and which canfurthermore be flexibly employed and, in particular, will overcome thecited disadvantages of known equipment for generating refrigeration.

Said object is achieved according to the invention by means of a powerstation having at least one steam turbine, whereby to generaterefrigeration at least one absorption-type refrigeration machine islinked to the steam turbine, with said absorption-type refrigerationmachine being operated by means of steam taken from the steam turbine,preferably from a low-pressure section of said steam turbine.

The invention proceeds from a consideration of the fact that powerstations which include a Rankine cycle offer very good initialconditions for integrating a refrigeration-generating device.

Owing to factors inherent in the system, power stations of this typeemploying a water-steam cycle contain a number of systems that can beused in a simple manner for coupling an absorption-type refrigerationmachine.

To generate refrigeration it is customary to employ a cycle in which aliquid refrigerant (such as ammonia, for instance) is expanded such thatit converts to the vaporous phase, then absorbing heat from a coolingchamber, a condensing-water cycle or another part of the system. Therefrigerant vapor is then condensed and said heat is given off againoutside the cited part of the system by means of cooling. Water isfrequently used as the refrigerant for air-conditioning systems as atnear-vacuum pressure it vaporizes at a temperature of approximately 4°C., meaning that an approximately 6° C. cold-water lead-in can be madeavailable to a condensing-water cycle.

According to the principle on which absorption-type refrigerationmachines operate, the coolant vapor is condensed by being absorbed in asolution (for example an aqueous lithium bromide solution if water isused as the refrigerant), then re-expelled by heating of the solutionand converted into the liquid phase. This means that instead of amechanical compressor, which is subject to wear-and-tear and consumesmechanical or, as the case may be, electrical energy, an expeller isemployed which is operated predominantly (or even exclusively) usingthermal energy, with dissipating of the heat absorbed duringvaporization and expulsion now playing a decisive role.

Said heat dissipation can advantageously take place in a cooling toweror cellular-type radiator of the kind present in any event in many powerstations, for example condensing power stations.

Just as in the case of generating heat for heating purposes, operatingan absorption-type refrigeration machine requires the presence of a heatsource preferably having a temperature of approximately 100° C. to 120°C. The present invention employs steam taken from the steam turbine asthe heat source.

When the invention is employed in a gas turbine or gas-and-steam powerstation, another conceivable heat source is the hot exhaust gas of thegas turbine, said hot exhaust gas being extracted in its streamingdirection, for example, behind or in the area of the end of a waste-heatboiler and used for the heat exchange with the heating medium.

The invention thus further leads to a power station which contains atleast one gas turbine and in which at least one absorption-typerefrigeration machine is linked to the gas turbine in order to generaterefrigeration, with said absorption-type refrigeration machine beingoperated by means of waste heat from said gas turbine.

In a power station of this type the absorption-type refrigerationmachine can advantageously be used, additionally or alternatively torefrigerating other consumers of refrigeration, for refrigerating intakeair for the gas turbine.

Very many existing power stations containing a steam turbine will permitsteam to be decoupled from the steam turbine by simple means and used tooperate an absorption-type refrigeration machine. Existing powerstations can thus in very many cases be expanded with modest effort toinclude the function of central refrigeration provisioning.

Apart from the necessary heat source for operating the absorption-typemachine, said machine also contains components that have to be cooled.Examples of these include a container under vacuum containing thepreviously cited lithium bromide solution and requiring to be cooled,and a condenser connected upstream of the vacuum.

These types of components of the absorption-type refrigeration machinethat require cooling can, for instance, be supplied with cooling watersimultaneously with a condenser of the steam turbine, said condenserbeing present in any event and supplied with cooling water, with saidcooling water being influenced by the ambient temperature and thushaving a temperature for the cited cooling purposes that is sufficientlylow. This can be, for instance, water taken from a river or other bodyof water in the vicinity of the power station. The surrounding area isthus a heat sink compared to the components requiring cooling so thatcooling water which is kept in said heat sink and routed to thecomponents being cooled is highly suitable for cooling purposes withoutthe need for further measures for, for example, lowering the temperatureof the cooling water. It is here that a major advantage of the inventioncan also be found, because in known devices for refrigerationprovisioning on a decentralized basis the problem often arises ofproviding a suitable cooling medium which is capable of absorbingsufficient energy in cooling the components being cooled.

A further advantage of the invention is that absorption-typerefrigeration machines are based on a robust and durable technologyrequiring at most the use of liquid circulating pumps and not involvingany gas compression as in the known compression-type refrigerationmachines. Absorption-type refrigeration machines therefore havevirtually no moving parts in their major components and consequentlyhave low maintenance requirements.

Absorption-type refrigeration machines furthermore require very littleelectrical energy themselves.

In an advantageous embodiment of the invention at least part of thesteam taken from the steam turbine can be routed to a heat exchanger forheating a heating medium, preferably hot water.

In this embodiment of the invention the power station has been expandedin such a way as to provide heat generation alongside refrigerationgeneration, with steam taken from the steam turbine now being used tooperate a heat exchanger, by means of which thermal energy is routed toconsumers of heat, as well as the absorption-type refrigeration machine.Examples of said consumers of heat include heating devices, for, say,buildings, that are operated by means of a flow of hot water. Thethermal energy needed to heat the flow of hot water is taken by means ofheat exchange from the steam taken from the steam turbine.

Combined heat, power and refrigeration generation for the centralprovisioning of consumers with electrical energy, refrigeration and heathas clearly been implemented in this embodiment of the invention.

The expeller of the absorption-type machine can be operated directlyusing the extracted steam or indirectly by means of heat exchange usingan expeller-heating medium, for example water. The extracted steam canalso be routed to an air-conditioning system, with said system having achangeover device by means of which the extracted steam can be routedoptionally to the expeller of the absorption-type refrigeration machine(for example for generating refrigeration in the summer for coolingpurposes) or to the heat exchanger (for example for generating heat inthe winter for heating purposes); the absorption-type refrigerationmachine and/or heat exchanger are here included in the air-conditioningsystem.

In a further advantageous embodiment of the invention the power stationfurthermore includes at least one gas turbine whose waste heat is usedfor generating operating steam for the steam turbine, with its beingpossible for the absorption-type refrigeration machine to be used,additionally or alternatively to refrigerating other consumers ofrefrigeration, for refrigerating intake air of the gas turbine.

This embodiment of the invention is what is termed a gas-and-steamsystem which includes the absorption-type refrigeration machine forgenerating refrigeration.

When the gas turbine is operated, air is taken in which advantageouslyhas to undergo cooling in order to enhance performance. In the presentembodiment of the invention the absorption-type refrigeration machine'srefrigeration generation is provided at least partially and/ortemporarily for said cooling of the intake air, namely especially incases of the power station's operation in which consumers requiringcooling that are linked to the absorption-type machine do not use up theabsorption-type refrigeration machine's full refrigeration potential sothat, consequently, surplus refrigeration is available which is thenused for cooling the gas-turbine intake air.

The performance of the gas turbine is enhanced thereby. Variations inthe quantity of refrigeration taken are also reduced thereby so as, inparticular, to ensure that the absorption-type refrigeration machineoperates evenly.

The proposed invention is suitable in all its embodiments for, forexample, air-conditioning residential areas, large apartment blocks,office buildings, industrial parks, hotels, hospitals, public facilitiesetc. Preferred application sites for the invention can be, inparticular, the earth's hotter climatic zones subject to such highambient temperatures as to make air-conditioning necessary and/ordesirable.

Further possible application sites include, for example, vacationcenters in tropical and subtropical regions.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is presented in more detailbelow with reference to the drawing, in which:

FIG. 1 shows a power station according to the invention embodied as agas-and-steam system, and

FIG. 2 shows a power station according to the invention having a gasturbine.

DETAILED DESCRIPTION OF THE INVENTION

The figure is a schematic of a power station 1 according to theinvention which is embodied as a gas-and-steam system and includes asteam turbine 5 and a gas turbine 30.

The operating steam B of the steam turbine 5 is made available by meansof the waste heat A of the gas turbine 30.

The steam turbine 5 includes a high-pressure section 7 and alow-pressure section 9.

An absorption-type refrigeration machine 10 is operated by means ofextracted steam 12 used as a heat source. Said extracted steam 12 isrouted to an expeller 14 of the absorption-type refrigeration machine10, said expeller sustaining the absorption process of theabsorption-type refrigeration machine 10. The output of the expeller 14is linked via a pump 41 to a heating surface 38 which is heated by thewaste heat A of the gas turbine 30 in order to generate the operatingsteam B necessary for operating the steam turbine 5. The exhaust gas ofthe gas turbine 30 is routed after heat exchange with the heatingsurface 38 to a cooling tower 36.

In the example shown the absorption-type refrigeration machine 10operates with a cycle for a lithium bromide solution which is circulatedand thereby heated by the extracted steam for feeding out liquid waterin the expeller 14 and is then re-cooled in a water vapor extractor 16for the absorption of water vapor. The water vapor extractor 16 is thusa component requiring cooling and is supplied with cooling water K whichis used, for example, in parallel for cooling a condenser 15 of thesteam turbine 5 and is taken from, for instance, a cooling tower 25.

The high-pressure section 7 and low-pressure section 9 of the steamturbine 5 are mutually connected in the present exemplary embodiment viaa heating surface 39 for intermediate overheating of the partiallyexpanded steam, for example.

The steam turbine 5 and gas turbine 30 are each coupled to a generator Gfor generating electrical energy. Refrigeration is generated by means ofthe absorption-type refrigeration machine 10 by means of a vaporizer 13which is under very low pressure, in particular pressure close to avacuum. Water requiring to be vaporized by means of the vaporizer 13will consequently be vaporized at a very low temperature, for example 4°C. The resulting steam is extracted from the vaporizer 13 by means ofthe water vapor extractor 16. Water ducted through the vaporizer 13 willas a consequence of the practically constant low temperature in saidvaporizer be cooled to a value approximating said low temperature sothat a stream 45 of lead-in cooling water for cooling consumers 32 ofrefrigeration is generated with a low constant temperature.

In the present embodiment of the invention the absorption-typerefrigeration machine 10 is furthermore used to operate a coolingsurface 34 by means of the stream of lead-in cooling water so thatintake air L for the gas turbine 30 is cooled. This enhances theperformance of the gas turbine. By combining the two measures, namelyprovisioning of the consumers 32 of refrigeration and cooling of theintake air L, it is also possible to achieve a constant quantity ofrefrigeration taken from the absorption refrigeration of theabsorption-type refrigeration machine 10.

The extracted steam 12 from the low-pressure section 9 of the steamturbine 5 is furthermore used to heat a heating medium 28 by means of aheat exchanger 20 so that consumers 27 of heat can be supplied withthermal energy by means of the heating medium 28.

The embodiment of the invention shown in FIG. 1 hence implementscombined heat, power and refrigeration generation suitable particularlyfor centrally provisioning a large number of consumers with the citedtypes of energy.

Similarly to the known long-distance thermal energy network associatedwith known combined heat and power generation, the invention furthermakes it possible to implement a long-distance refrigeration network forthe central provisioning of refrigeration and hence to realize, forexample, the air-conditioning of large building complexes having asubstantial need for refrigeration.

This is of particular interest in the earth's hotter climatic zoneswhere there is a substantial need for refrigeration andair-conditioning. Using the invention will ensure provisioning withelectrical, thermal and refrigeration energy.

FIG. 2 shows a power station 50 according to the invention having a gasturbine 52 whose heat AH is routed to a waste-heat boiler AHK; the wasteheat AH leaving the waste-heat boiler AHK is here used for operating anabsorption-type refrigeration machine 100. The embodiment and furtherconnection of the waste heat boiler are not shown in greater detailhere, nor are further specifics of the power station 50.

1. A method for using a power station for conditioning air, comprising:operating a steam turbine having a low pressure section; operating a gasturbine with waste heat therefrom used to generate operating steam forthe steam turbine; fluidly connecting an absorption-type refrigerationmachine to the steam turbine; extracting steam from the low-pressuresection; using the extracted steam to operate the absorption-typerefrigeration machine for centralized air-conditioning of a structureand fluidly connecting the absorption-type refrigeration machine to coolintake air for the gas turbine.
 2. The method according to claim 1,wherein the structure is a building.
 3. The method according to claim 1,wherein the structure is a plurality of buildings.
 4. The methodaccording to claim 1, wherein the structure is a housing at the powerstation.
 5. The method according to claim 1, wherein at least a portionof the steam taken from the steam turbine is routed to a heat exchangerfor heating a heating water.
 6. A method for using a power station forgenerating refrigeration air, comprising: operating a gas turbine;operatively connecting an absorption-type refrigeration machine to coolintake air for the gas turbine; and operating the absorption-typerefrigeration machine with waste heat from the gas turbine forcentralized air-conditioning of a structure.
 7. The method according toclaim 6, wherein the structure is a plurality of buildings.
 8. Themethod according to claim 6, wherein the absorption-type refrigerationmachine is used additionally to refrigerate additional consumers ofrefrigeration.